aircraft for reduced impact on climate - dlr portal€¦ · aircraft for reduced impact on climate...

Regina Egelhofer

First CEAS European Air and Space Conference

Berlin, 10-13 September 2007

Aircraft for Reduced Impact on ClimateHow Aircraft Design can Contribute to Mitigating Global Warming

Technische Universität MünchenTechnische Universität München

2Berlin, 12 September 2007Regina Egelhofer - Technische Universität München

Acknowledgements

To

Gaby Rädel and Keith Shine (University of Reading)Marcus Köhler and Helen Rogers (University of Cambridge)Alain Joselzon (Airbus)Dan Allyn (Boeing)Paul Peeters (Breda University of Applied Sciences)

for providing data and figures to the talk.


Airplane with minimum climate impact?

Safe (parachute mandatory)?

Comfortable?

Fast?

Independent of the weather?

Can I put two suitcases in?

Good service?

Inexpensive?

Can I go from Munich to Berlin?

Photo credits: www.whiteplanes.com


Outline

1. Introduction

2. Aircraft emissions and their impact on climate

3. Mitigation options on the part of the airframe

4. Aircraft design methodology with full integration of climate impact

5. Conclusion


local

Introduction Definition of “Environment” linked to A/C operations

Noise Emissions

local global

Aviation

Environmental Impact

Local air qualityCommunity health Climate change

Tradeoffs Tradeoffs

Tradeoffs

Metrics?to enable tradeoffs

Regulations, Charges, external costs


Introduction Regulatory constraints

Source: Boeing

Development of emission regulations similar?

What is the delay?


Outline

1. Introduction




5. Conclusion


Aircraft emissions

Relevant Emissions from Aviation

1 kg Fuel

3.4 kg O2 1.23 kg H2O

3.16 kg CO2

In variable quantities:

Nitrogen oxides NOx ~ 4 - 40g

Sulphur oxides ~ 0.6 - 1g

Particles / soot ~ 0.01 - 0.03g

Contrails

forms / depletes ozone O3

depletes methane CH4

Ozone and methane are greenhouse gases.

Greenhouse gases


Climate Impact of Aviation

From Sausen et al in Meteorologische Zeitschrift, Vol. 14, Number 4, 2005

Aircraft RF until 1992 / 2000


Outline

1. Introduction




5. Conclusion


Simplified Aircraft Design Functional Chain


Manufacturers’ views (1): mitigation potentials

Example of Aerodynamics Performance Improvement – Winglets

⇒ The improvement depends on the individual mission.

Structural weight reductions referred to 1990 baseline:

– 8% until 2005

– 15% until 2010 (A350 / 787 aircraft types)

– Future?

From ICCAIA: “The Manufacturers’ Perspectives”, International Civil Aviation Day, 7 Dec. 2005, and ICAO Colloquium on Aviation Emissions, May 2007

at MTOW+1000 lb≈

at fuel capacity limit+6000 lb≈Payload at fixed range

1500 nm mission-4.60%≈NOx Emissions

1500 nm mission-3.50%≈

500 nm mission-2.50%≈Fuel burn

+130 nautical miles≈Design range

Airliners.net



“Breakthroughs for fuel burn reduction are possible”

• Aerodynamics: up to 10 % of fuel– Advanced riblets

– Wave drag control

– Natural or hybrid laminar flow

– Innovative aircraft configuration

• Weights: up to 5% of fuel– Next generation composite design and manufacturing

• Systems:– 30% energy reduction of ECS identified by using low pressure bleed

– On-board systems optimisation offers an additional potential fuel burn benefit.

– 3% of fuel burn in cruise through fuel cells

• Changing cruise altitude– Lowering cruise altitudes “might help for NOx, but increases fuel burn up to +6% (for 4000ft cruise

altitude reduction at M0.85)”

– Better knowledge on contrails and cirrus needed to enable tradeoffs with fuel burn

• Biofuels, may become standard complement to oil kerosene.

Summarised from Alain Garcia: Technical Press Briefing, Airbus, April 2007Also in Aviation Week and Space Technology, August 20/27, p. 60.



New technologies:

• Next generation composites

• Reducing pneumatic systems

• Biofuels with priority of BTL

Airplane performance improvements (ongoing programs):

• Increased precision navigation for operational efficiency (737 NG)

• Lighter weight carbon brakes (737 NG)

• Blended winglets (737 NG): 3-5% aerodynamic efficiency / 2-4% in fuel burn

• Advanced wing design: raked wing tip, smaller wing vortex generators, revised ram air inlet for lower drag (777)

• Manoeuvre load alleviation for lower empty weight (777F)

At least 15% improvement in fuel efficiency is required by the market in order to justify the development of a new generation of airplanes.

Summarised from Boeing: Aviation and the Environment - Our Commitment to a Better Future, August 2007


Alternative views (1)

Increasing L/D

Increase span. Wing weight ↑ - stronger lightweight materials, reduced Mach could compensate

Radical solutions:

–Blended wing body

–Natural laminar flow control

–Hybrid laminar flow control (HLFC)

–Full (all-over) laminar flow control

From Prof. Jeff Jupp: The Impact of Aviation on the Environment – How will the future for Air Transport be Affected? RAeS lecture at the Technical University of Munich, 14th of June 2007

Also see:

Aeronautical Journal, Aug 2006

Greener by Design, The Technology Challenge, 2001

Greener by Design, Mitigating the Environmental Impact of Aviation: Opportunities and Priorities, 2005

Greener by Design

LFW with open rotor and 15% reduction in empty weight

Laminar Flying Wing

Blended Wing Body

Tailplane, Fin, Nacelle

Increase from 15% to 65% in CFC structural component


Alternative views (2)

From Greener by Design: Mitigating the Environmental Impact of Aviation: Opportunities and Priorities, Report 2005

Peeters et al., TAC Conference 2006

Fuel efficiency is only one of many design requirements of commercial aircraft.


Outline

1. Introduction




5. Conclusion


What’s the point?

Fuel consumption depends on the mission (operations).

And: Climate impact does not only depend on the quantities emitted, but also on where the gases occur. That’s why we need to couple aircraft design with operations and we need an atmospheric / climate metric.


Distribution of aircraft emissions

Figure from DLR

It is important, where the aircraft fly!Most important parameter: altitude

⇒ Interdependence with classic aircraft design parameters


Aircraft design today

Simplified Aircraft Design Functional Chain (2)

Aircraft design tomorrow

Weights

Lift

Drag

Thrust

Consumption

Emissions

Atm. Impact

Aerodynamics

Engine Technology

Configuration

Structures

Parameter ?

Design Loop

Weight

Lift

Thrust

Drag

Noise


ALT

Climate Impact

Design approach including global warming

Aicraft Design / Perf.

Emission scenarios

Climate impact eval. Operations

Impact-driven instead of emissions-driven design!

Credits: Eurocontrol

Holistic approach at system level


1995 Reference 2005 Reference 2005 Virtual DeltaAvailable Seat Kilometres (ASK) [1012] 3.00 3.72 3.75 0.8%Estimated Load Factor [-] 69% 75% 75%Total flown distance from OAG [109 km] 13.97 16.55 16.55Considered number of flights in OAG [million] 10.5 11.2 11.2Total flown distance calculated [109 km] 13.58 16.09 16.11 0.1%Fuel consumption [Tg] 73.5 84.4 91.2 8.1%NOx emissions [Tg] 0.90 1.12 1.14 1.2%Global NOx emissions index [g/kg] 12.21 13.33 12.48 -6.4%Average seat capacity [-] 215 225 227Average sector length [km] 1329 1479 1479Consumption/100ASK [kg] 2.45 2.27 2.43Consumption/100RPK [kg] 3.55 3.02 3.24Consumption/100RPK [l] 4.44 3.78 4.05 7.3%

Example 1: Benefit of fleet renewal 1995-2005

Detailed results in Egelhofer et al., 2007, Journal of Air Transportation, Vol. 12, No. 2, in print.

Virtual scenario: 2005 traffic, 1995-type fleetOnly routes that existed in both years (OAG)

Operations included


Atmospheric evaluation: LEEA project (1)

From: Köhler et al., TAC Conference 2006, Oxford

LEEA: Low Emissions Effect Aircraft. Project sponsored by DTI (UK) and Airbus

5km

15km

AL

TIT

UD

E

• Complicated processes in the atmosphere

• Simple atmospheric metrics (Kyoto GWP) not sufficient to represent aviation’s climate impact.


Atmospheric evaluation: LEEA project (2)

From: Rädel and Shine, TAC Conference 2006, Oxford

Ozone forcing per TgN (ALT)

LEEA: Low Emissions Effect Aircraft. Project sponsored by DTI (UK) and Airbus

Only ozone forcing, methane effect not included!


Example 2: Climate impact of combustor techn.

More details in: Egelhofer et al., published at SAE AeroTech 2007 Conference, paper 2007-01-3807

2000 nm Flight altitude Distance Fuel burn Climate impact ratioTaxi and Takeoff 750 0% 3% 1Climb 18750 7% 14% 1.20Step 1 36000 13% 13% 0.96Step 2 38000 70% 63% 0.95Step 3 40000 4% 3% 0.94Descent 20750 6% 2% 1.01Landing and Taxi 750 0% 2% 1

Total 100% 100% 0.96

Climate impact ratio (based on LEEA):Impact Combustor StandardImpact CombustorNox Low

Climate metric included

*

* 1995-1996 technology level: Double annular combustor ./. single annular combustor


Drawbacks and open questions

• Complexity: Data management and uncertainties

• Lack of appropriate / reliable metrics at several levels

• Which metrics could allow tradeoffs to non-environmental issues (monetary / regulations)?

• Competences within industry (atmospheric sciences)?

• Competences within sciences (aircraft design and operations)?

Continue existing and create new research cooperation


Outline

1. Introduction




5. Conclusion


Airplane with minimum climate impact?

from John P. Fielding: Introduction to Aircraft Design

We should re-open the design space:

• Design Range?

• Speed?

• Cruise altitude?

of today’s aircraft are no premises.Airc

raft

Des

ign


Conclusion

Rebalancing the importance of the atmosphere presumes reliable metrics (need for development / improvement / validation).

Engineering shall keep the pace of atmospheric scientists in order to be able to integrate new knowledge as quickly as possible.

Any financial penalties and restriction systems have to be coherent and goal-orientated.

All stakeholders of the air transport system must work hand in hand (systems approach).

The early consideration of the environment in aircraft design will be vital for the manufacturer, once regulations represent the actual impact.

Anticipating political conditions and designing respective aircraft will then provide an economic asset and competitive advantage for the aircraft manufacturer.

The social acceptance of aviation could increase, if advances are appropriately communicated (!).

Aviation should not be afraid of new environmental regulations, but take advantage of them as drivers for innovation.

Let’s go back to work!


References

Advisory Council for Aeronautics Research in Europe, Strategic Research Agenda 2 (SRA2), 2004, available on http://www.acare4europe.org.Berntsen, T.K., J.S. Fuglestvedt, M.M. Joshi, K.P. Shine, N. Stuber, M. Ponater, R. Sausen, D.A. Hauglustaine, L. Li, “Response of climate to regional emissions of ozone

precursors: sensitivities and warming potentials”, Tellus, 57B, 283-304, 2005.Egelhofer, R., C. Bickerstaff and S. Bonnet, “Minimizing Impact on Climate in Aircraft Design”, SAE AeroTech 2007 Conference and Exhibition, Los Angeles, Sept. 2007.Egelhofer, R., C. Marizy and C. Cros, “Climate Impact of Aircraft Technology and Design Changes”, Journal of Air Transportation, Vol. 12, No. 2, in print, 2007.Eyers, C. J., P. Norman, J. Middle, M. Plohr, S. Michot, K. Atkinson, R.A. Christou, AERO2K Global aviation emissions inventories for 2002 and 2025, Final report, EC

project G4RD-CT-2000-00382, 2004.Garcia, A., Airbus Holistic Roadmap to the Future, Airbus Technical Press Briefing, April 2007.Greener by Design, Air Travel – Greener by Design, The Technology Challenge, Royal Aeronautical Society, 2001.Greener by Design, Mitigating the Environmental Impact of Aviation: Opportunities and Priorities, Royal Aeronautical Society, 2005.Intergovernmental Panel on Climate Change (IPCC), Aviation and the Global Atmosphere, Special Report of IPCC Working Groups I and III, J.E. Penner et al. (Eds.),

Cambridge University Press, Cambridge, 1999.Intergovernmental Panel on Climate Change (IPCC), Working Group I: The physical basis of Climate Change, Fourth Assessment Report of the IPCC, 2007, available on

http://ipcc-wg1.ucar.edu.International Coordinating Council of Aerospace Industries Associations, Reducing Aviation Emissions – The Manufacturers’ Perspective, International Civil Aviation Day, 7

December 2005.Joselzon, A., Fuel Conservation – A manufacturer’s perspective, ICAO Colloquium on Aviation Emissions with Exhibition, May 2007.Jupp, J., The Impact of Aviation on the Environment - How will the future for Air Transport be Affected?, Lecture at Forum der Luft- und Raumfahrt, Technische Universität

München, June 2007.Köhler, M., O. Dessens, O. Wild, H. Rogers, J. Pyle, “Changes in Ozone and Methane due to Aircraft NOx: Sensitivity to Cruise Altitude”, International Conference on

Transport, Atmosphere and Climate (TAC), Oxford, Great Britain, 2006, Proceedings in print.Rädel, G., K. Shine, “Sensitivity of Radiative Forcing due to Aircraft Altitude”, International Conference on Transport, Atmosphere and Climate (TAC), Oxford, Great

Britain, 2006, Proceedings in print.Sausen, R., I. Isaksen, V. Grewe, D. Hauglustaine, D. S. Lee, G. Myhre, M. O. Köhler, G. Pitari, U. Schumann, F. Stordal, C. Zerefos, “Aviation radiative forcing in 2000: An

update in IPCC (1999)”, Meteorologische Zeitschrift, 14, 555-561, 2005.Schumann, U., “Aircraft Emissions“, In: I. Douglas (Ed.), Encyclopedia of Global Environmental Change, John Wiley & Sons, Ltd, Chichester, 2002, pp. 178-186.Shine, K.P., J.S. Fuglestvedt, K. Hailemariam, N. Stuber, “Alternatives to the Global Warming Potential for comparing climate impacts of emissions of greenhouse gases”,

Climatic Change, 68, 281-302, 2005.

Thank you for your attention!

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